This invention was made with Government support and the Government may have certain rights in the invention.
1. Field of the Invention
The present invention relates to optical components and instruments. More particularly, it relates to a mount for an optical component.
2. Description of the Related Art
In many optical instrument designs, mounts are employed to secure certain optical components at precise positions with respect to other optical components within the instrument in order to ensure optimal performance of the optical instrument. A beamsplitter is one such optical component that in certain applications must be aligned at a precise position within an instrument. Examples of conventional optical instruments employing beamsplitters are Michelson-type transform spectrometers, Michelson interferometers and laser range finder/designator (LRF/D) systems. If the beamsplitter is not aligned within a precise range in each of those systems, light beams that are divided by the beam splitter will in turn be out of alignment with respect to other components resulting in inadequate performance of the instrument.
A variety of different designs for mounting optical components in instruments are known in the art. Some optical component mounts are based upon securing the optical component on an adhesive silicone tip or layer. However, the adhesive condition and resulting performance of the mount can change over extended periods of time. Mount designs that are more reliable for critical optical components over extended periods of time and under severe conditions are based upon the use of metal clips and flexure supports. The flexure supports provide a resilient connection for the optical component to a support structure.
Conventional optical component mounts utilizing a clip and flexure mount employ a three-point mount design. Two conventional three-point flexure mounts for a circular optical component are illustrated in FIGS. 1a and 1b. In both designs, the three-point flexure mount includes flexures that are circumferentially spaced from each other by about 120xc2x0. In the mount design depicted in FIG. 1a, flexures 32 are secured to an outer surface of a frame 34, and an optical component 30 is in turn secured to frame 34 at three clip points 36. In the mount design of FIG. 1b, the optical component 40 is secured to three flexures 42, and flexures 42 are in turn secured to an inside surface of a frame 44. Each flexure in the three-point flexure mount design depicted in FIGS. 1a and 1b provides a direction or line of freedom for movement of the optical component as indicated by the dashed lines in those figures. Each line of freedom extends perpendicular to the flexure to which it relates. In the examples illustrated in FIGS. 1a and 1b, the lines of freedom intersect at the center of the circular optical component. The intersection of the lines of freedom is referred to as the stationary point for the optical component, which is a point on the optical component that remains substantially fixed despite thermal expansion or vibratory movement of the optical component. The three-point flexure mount design works well for optical components having a circular configuration, and accordingly have been used extensively as the preferred type of mount.
Because of their prevalent use, three-point flexure mount designs are also utilized for optical components having noncircular geometric configurations. A conventional mount design for a generally rectangular shaped optical component is illustrated in FIG. 1c. The mount design includes a frame 54 secured to a base plate 56, with one flexure 52 aligned at one end of the frame and two flexures 53 aligned at the corners of an opposing end of the frame. Optical component 50 is secured within the frame 54. As indicated by the dashed lines of FIG. 1c, the lines of freedom allowed by the three flexures intersect to form a stationary point at a location removed from the center of the optical component.
While three-point mount designs may perform adequately in certain environments when the size of the optical component is small, the performance of such mounts degrades considerably when larger optical components are utilized and severe thermal and vibrational conditions exist. For example, three-point mount designs have been found to be unsuitable for maintaining appropriate alignment of a large optical component such as a beamsplitter in an instrument secured within a satellite or other aerospace vehicle subjected to typical harsh launch conditions. Additionally, devices utilized in the semiconductor and related industries for manufacturing micro-components requiring a high degree of manufacturing precision can degrade in performance when using three-point optical component mounts in applications where the devices are exposed to high temperature changes and/or vibrations. The flexures, when configured in the mount of FIG. 1c, are incapable of preventing the optical component from undergoing distortion and ensuring a sufficient optical flatness for maintaining a desired performance level. This problem is especially prevalent for the conventional rectangular mount depicted in FIG. 1c, where the stationary point of the three-point flexure mount is located away from the center of the optical component. While the flexures of these mounts may be stiffened, e.g., to survive vibration levels associated with a typical launch, thermal variations (i.e., temperature changes of more than 80xc2x0 C.) associated with the launch will create an undesirable flatness distortion in the optical component due to the thermal expansion of the optical component and/or supporting structure. In certain aerospace applications, e.g., a flatness distortion of only as much as about 0.1 microinch is allowable. Conventional three-point flexure mounts have not been able to maintain such a flatness tolerance under extreme temperature and vibrational conditions. In addition, conventional three-point flexure mounts for large, non-circular optical components can lead to a gravity sag at the unsupported portions of the component between the flexure mounts.
A further problem associated with conventional optical component mount designs is that they typically occupy a large area and are unsuitable for aerospace instrument designs that require strict size and mass limitations.
Thus, there is a need for an optical component mount that sufficiently maintains the alignment and flatness of the optical component within an instrument with a high degree of precision while under severe thermal and vibrational conditions. Further, there is a need for an optical component mount that is configured to occupy an area suitable for a particular application.
Therefore, in light of the above, and for other reasons that become apparent when the invention is described, an object of the present invention is to mount an optical component securely within an instrument so as to ensure a desired performance level of the optical component under severe thermal and vibrational distortion conditions.
Another object of the present invention is to minimize flatness distortion exerted on the optical component during exposure to such severe thermal and vibrational distortion conditions.
A further object of the present invention is to securely mount the optical component within the instrument utilizing a mount having a small size and mass suitable for aerospace or other applications.
Yet another object of the present invention is to provide an effective mount design capable of securing multiple optical components within an instrument.
The aforesaid objects are achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto. In accordance with the present invention, a mount for ultra-high performance of optical components subjected to severe thermal and vibrational distortion conditions is provided. The mount includes a first pair of supports each disposed along a first axis intersecting a center of the optical component, where the supports of the first pair couple with the optical component and are movable in a direction of the first axis. The mount further includes a second pair of supports each disposed along a second axis intersecting the optical center of the optical component, where the supports of the second pair couple with the optical component and are movable in a direction of the second axis. Each of the supports of the first pair are substantially rigid in directions non-parallel the first axis, and each of the supports of the second pair are substantially rigid in directions non-parallel the second axis The supports thus limit the freedom of movement of the optical component around a stationary point located at about the center of the optical component.
The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of a specific embodiment thereof, particularly when taken in conjunction with the accompanying drawings wherein like reference numerals in the various figures are utilized to designate like components.